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 ENVIRONMENTAL 
RESULTS 

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 ABOUT THE ZONE 

Boat Creek is a small mangrove-lined estuary connected to the western side of the Western Basin. 

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 WATER & SEDIMENT 

Boat Creek received an overall water quality score of 0.82 (B). 

Sediment quality of Boat Creek was very good with an overall score of 0.91 (A).

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The following graphs compare the Water and Sediment scores reported for 2024 (top line) to those from 2023.

WATER

SEDIMENT

Very good (0.85-1.00)

Poor (0.25-0.49)

Good (0.65-0.84)

Satisfactory (0.5-0.64)

Very Poor (0.00-0.24)

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No data available

Overall, Water quality in Boat Creek scored 0.82 and received a good grade (B), an improvement on the 2023 report card (0.69, good (B)). This score was calculated by aggregating the three sub-indicator and associated measure scores (Physicochemical – pH and turbidity, Nutrients – total nitrogen, total phosphorus and dissolved metals, and dissolved metals – aluminium, copper, lead, manganese, nickel and zinc). 

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Within the Physicochemical sub-indicator, Boat Creek received a score of 1.00 and a very good grade (A) for pH, indicating that the average pH was well within the guideline value range. This zone received a score of 0.65 and a good grade (B) for turbidity in 2024, improving on the score of 0.36 and poor grade (D) for turbidity in 2023. 

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Within the Nutrient sub-indicator group, total nitrogen (0.49) received a poor grade (D), while total phosphorus (0.60) improved from a very poor grade (E) in 2023 to a satisfactory grade (C) in 2024. Chlorophyll-a (0.83) remained a good grade (B) in 2024, indicating that average concentrations for chlorophyll-a were below the guideline value for this zone. 

All six Dissolved metals received high scores (1.00) and very good grades (A) indicating that concentrations were well below the water quality guideline values. 

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For Sediment quality, Boat Creek received an overall score of 0.91 and a very good grade (A), a similar result to the previous year. This score was calculated by aggregating measure scores (Metal and metalloids – arsenic, cadmium, copper, lead, mercury, nickel and zinc). 

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In 2024, five of the seven Metal and metalloid sub-indicator measures received very high scores (1.00) and very good grades (A), while two measures – arsenic and nickel – received scores of 0.71 and 0.65 respectively, both a good grade (B). These results reflect that all concentrations were below the guideline values for this zone. 

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 HABITATS 

MANGROVE RESULTS

Overall, the grade for Mangroves improved from a poor (D) in in 2019 to a good (B) in 2024 at Boat Creek, a result of improvements in scores and grades for all three measures. Mangrove extent improved from a satisfactory (C) in 2019 to a good grade (B) at Boat Creek in 2024. The grade for canopy condition at Boat Creek improved from a poor (D) in 2019 to a good (B) in 2024. Shoreline condition of mangroves at Boat Creek improved in grade from a poor (D) in 2019 to a satisfactory (C) in 2024. 

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 FISH & CRABS 

 FISH RECRUITMENT RESULTS 

Fish recruitment was assessed for two species: Yellowfin bream Acanthopagrus australis and Pikey bream Acanthopagrus pacificus. The Fish recruitment grade for Boat Creek remained a satisfactory (C) in 2024. 

 MUD CRAB RESULTS 

The overall grade for Mud crabs at Boat Creek remained a good (B). While abundance improved from a poor grade (D) in 2023 to a very good grade (A) in 2024, sex ratio grades were lower, decreasing from good (B) to poor (D). 

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